9/9/15 10:56 AM

My 1975 Raleigh Grand Prix Mixte project is progressing to the point where I am planning to touch up the paint. It was garage kept for, what, 28 years by the original owner. Only last winter did I do it the disservice of storing it on a covered balcony. As a result all the dings developed superficial rust, no scaling.

I was thinking of using a q-tip to dab the household solvent CLR to the rusty dings. Obviously I'd start small and hidden.

The bike is painted a simple white. After rust removal I'd like to match the paint without going overboard. I was thinking of masking larger dings, using a gray primer and then applying the white the next day, pulling the tape before it cures. Spraying is not an option, even at masked-off touch up volume.

As for matching the paint, I live near a big hobby store and was going to try a high quality oil enamel. Perfection can't be expected but I was thinking get a large white base and working with black and primaries, maybe an ocher and getting something in the neighborhood by matching under the bottom bracket and chain stays. I live near any number of hardware, paint stores, and auto body places.

TIA

9/9/15 11:01 AM

how big are the areas needing touching up. up to 1/4" diameter? 1/2"?

I do a technique called drop filling on guitars using a toothpick. On bikes I have used nail polish after rust abatement, oil based primer, then the nail polish. The color choices for mail polish is off the charts! I found exact match for my Saroni Red Nago which had spent about a year in a garage with no wheels on it. Had some real down to metal thin long scraps..

There is Loctite rust products, one normal jelly and an called Extend. If you have any pitting in the metal the Extend used with q-tips, then a serious wax/grease removal of your choice, oil primer that is for old steel and rust, then paint is what I have done as pretty permanent repairs before when warranted.

I mask like crazy so as not to effect good areas nearby....

And neutralizing the rust chemically I highly recommend, else stuff comes back. or worse rust down into the metal under the paints. Thus a primer that is for old steel should be considered as applicable.

9/9/15 5:41 PM

My general rule for paint chip touch-ups is to use a toothpick like Bob just mentioned, and to only fill the chip area, never to overlap the edges.

I'm not taking rust neutralization into account, but I suppose one could apply a penetrating primer of some sort as a first step, followed by color.

Here the humidity is so low that I just cover the defects so as to minimize their visible size.

For metallic paints, I start with a metallic silver, just a few drops in an empty bottle, to which I add and mix drops of colored paint to match the bike.

9/10/15 10:17 AM

Rustoleum sells rust conversion primers, which I've found to work well on cars, so they should be good on steel frames, too. It's a chemical conversion process that doesn't require rust removal first, other than any loose flakes.

Citric acid (available at wine/beer making suppliers) is a thorough, but gentle and safe rust remover that I've used extensively when refurbishing old tools (planes, chisels, etc.). It could be used as a wipe-on rust remover on frames and for soaking small parts like screws and springs. Surfaces need to be protected immediately after cleaning, as they are highly reactive.

There are also "metal prep" products designed for auto body repairs, but they tend to be much less "user friendly". I generally don't use them anymore and they seem like overkill for bikes.

Harbor Freight sells an inexpensive system for glass etching (it's like an airbrush) that should be great for removing rust in hard-to-reach areas.